Every once in a while, something new comes along that whacks you upside your head so hard you stand silly shocked still. Maybe it's nature's way of resetting your synapses to accept the wonderfully unexpected. Like, for instance, your first listen to the TacT Audio Millennium amplifier. The result of a joint research effort between Toccata Technology, a Danish company, and TacT Audio (www.tactaudio.com), the Millennium amp qualifies as a true breakthrough in audio reproduction. The Millennium's trade secret circuitry and patented firmware are an in your face harbinger of digital audio playback's future. The Millennium's $9,800 asking price may also shock. But the Millennium is a combination stereo amplifier, preamplifier, and digital analog converter all rolled into one great high-end package, so its hefty price tag really isn't so out of line.

The Millennium is not a conventional amplifier that transforms a small analog representation into a honking big analog facsimile. There is absolutely no analog amplification or conventional D/A conversion anywhere inside the Millennium. As to why you would ever want an all-digital amplifier, ask yourself this: If the source is digital, and/or the input signal is digital, then what else should be driving your speakers other than a pure digital power source? Thus the inevitability of a product like the Millennium; an output voltage regulation machine that directly converts digital signals into speaker power. The Millennium is a powerful blow to your cherished and erroneous high-end notions. When a torrent of Millennium-liberated-at-last bits begin streaming over the speaker wires, it's a shock to the system "g to yours, bubby, not the speakers.

Reviewers love to talk about sound emerging from "black space", audio devoid of background noise, distortion, or interference. But even deepest outer space has a huge amount of invisible "dark energy" floating around, warping space and time. The same extra crap fact of life applies to our conventional amplifier universe. All that analog junk floating between the original digital input and the speaker outputs ultimately distorts the listening experience. Listening "though" the Millennium is like emerging from Plato's bat cave. A blinding amount of detail is painted across a shockingly expanded soundscape. It's like the initial shock of tasting real French Normandy butter after years of wolfing down chem-pasteurized concoctions that come in crappy plastic tubs. Once you have tasted the real deal you can never go back to faux musical spreads.

The Millennium is pretty near obsolescence-proof. When another digital audio format gets established, simply jack in the new processing software from TacT, which at some point you will be able to download off the Net. The Millennium has an internal 96kHz/24bit resolution and is upgradeable to 400kHz/24 bit. It doesn't matter to the Millennium whether it's processing 16-bit Red Book CD's, a 192 kHz DVD-audio disc, Sony's new Direct Stream Digital (Super Audio CD) system, or whatever. Bits are bits, and smart algorithms rule the Millennium's day. So forget about stupid hardwired hardware that gets chucked onto the scrap heap every time the industry decides to foist a YAS (Yet Another Standard) on hapless consumers. [BTW, forget about PCs obviating the need for a TacT-type unit. The problems with using a general purpose PC as a high-end digital audio processor are many, not the least of which are their el cheapo power supplies and the hellish, unshielded electrical noise inside the case. You might as well try staging an opera inside a steel mill.]

The Millennium certainly looks like it can last through more than a few digital format wars as it's built like the proverbial tank. The big, heavy (it tips the scales at 62 pounds), Millennium is CNC-machined out of aluminum billets with a precision of 0.2 mil (only the top and bottom covers are plate aluminum). The front panel is a bullet stopping one and a quarter inches thick and is Bauhaus minimal with just three buttons and a big circular display. Its three-inch round glass display visually dominates the brushed aluminum frontispiece. Encircling the display is the volume control ring, a very expensive feeling, silky smooth device that spins like a perpetual motion machine thanks to its mil-spec ball bearing races. Because its circular volume control spins so easily, a Max-volume setting should be set via the TacT remote control. Otherwise, one easy spin of the dial and you just blasted all your good neighbor relations good-bye.

At the rear of the Millennium are five digital inputs: 3 S/PDIF (1 RCA, 2 BNC), 1 AES/EBU, and 1 TacT Clock Link. The two BNC connectors can also take RCA connectors if a BNC-RCA converter plug is used. Because the standard issue Millennium accepts only digital inputs, you must use an outboard A/D converter to plug in an analog device, like an LP playback system, or maybe you still happen to love 8 track tapes. However, a Millennium configuration with four analog inputs is optionally available. An RS 232 communication link for a PC is standard, though. The Millennium also sports a special 5-pole XLR input at its rear to accept a clock-synchronized CD-transport. This setup effectively eliminates jitter all along the signal chain, all the way from the CD transport out to the speaker wires.

So what CD transport did we use to feed the big bucks Millennium? Ironically, it was a Radio Shack 3400 portable CD player that caused such a high-end ruckus several years ago. When used as a CD transport, especially when supported on a Black Diamond mini-Shelf, in turn sitting on three of "Those Things" from Black Diamond (a BD cone with a tiny Shelf structure affixed to it) the sadly out of production rat Shack 3400 remains an awesome high-end bargain. But even if we had used a mighty Krell or Levinson transport, there would still be no way to make the Millennium Millennium's power supply give any more voltage than it can produce, not even by an input signal charging hard at full input level. The absolute volume level delivered by the Millennium is totally determined by the source level input. The big circular volume dial is used only to set the power supply's output voltage. (Even further unlike conventional digital volume controls, redithering is not required in the Millennium.) So if the CD is recorded at a ridiculously low level, the worst that will happen with the Millennium is the system won't go lease busting loud.

But such low-level CD circumstances are rare and we never encountered a situation where the Millennium wasn't able to call up as much power as needed from the digital engine room. The Millennium is rated at a continuous 150 watts per channel into 8 ohms, and 250 watts into 4 ohms. Notably, this power is delivered without any negative feedback. Because it uses a switching power supply, the Millennium operates at a cool to the touch 90% + efficiency. (Using very efficient switching power supplies in high-end units like the Millennium is not new, e.g., the highly regarded Spectron amps.)

By now, you should have figured out that the Millennium can't clip in the normal sense of the term. You just run out of available level. (The Millennium won't voltage clip, but it may current limit.) Clipping has always been a dirty business in conventional transistor amps. When driven past the point of no-watts-left return, the resulting solid-state clipping can be nasty on the ears. In contrast, tube amps gracefully bow out of the sonic act rather than abruptly exit stage left via a hard clip, resulting in an often more pleasant musical experience. But with the no-clip Millennium, even the stuff that comes in glowing glass bottles may also acquire a slightly bitter taste.

At the core of the Millennium is a methodology called pulse width modulation (PWM). Rather than amplifying an analog signal by controlling varying degrees of output voltage and/or current from the power supplies, modulation of the signal is based on the time, or width, that the input signal is on or off. The Millennium takes an ordinary pulse code modulated signal and turns it into a pulse width modulated data stream. [PWM is a circuit used in converters to regulate output voltage. Regulation is achieved by varying the conduction time of the transistor switches. Stated another way, it is a switching power conversion technique where the on-line (or width) of a duty cycle is modulated to control power transfer for regulating power supply outputs. Therefore, in a pulse width modulated system, time, not signal intensity, rules the power supply roost.]

At the heart of this particular PWM implementation is a patented algorithm TacT calls "Equibit". The processor in the Millennium enables the Equibit algorithm to digitally select the correct pulse width combination from among 256 possible width choices. The analog waveform is output only after the optimal result is computationally determined. The Spectron is also a pulse width modulated amplifier but it uses an analog technique to control the pulse widths. The Millennium is thus the first switching "amplifier" to digitally unlock the great bit vault.

TacT recommended using the original Millennium Mk1 with speakers that were reasonably sensitive. Any speaker with a rated sensitivity above 88 dB produced quite good results. But the Millennium Mk2 is able to play 6-11dB louder and drive even more demanding speaker loads. In addition, the Equibit technology has been refined in the Mk2. The noise level has been reduced by 2 dB and the sideband distortion by 20 dB. (An Mk2 upgrade kit is also available for the Mk1.)

For this review, we used the only-pair-known-to-be-in-America, Greek-made Analysis Omega full range ribbon loud speakers. These are 6-foot tall, 2-inch thick bipolar radiators that use ribbons for both treble and bass. Big ribbon speakers are notoriously load-sensitive, and we had been driving the Omega's with a 300-watt/channel Sunfire amplifier. This is a great amp. It also has the typically high damping factor of a big transistor job. On a pure this-will-never-work whim, we swapped out the Sunfire for the TacT. The speed of the ribbons coupled with the incredible speed of the Millennium resulted in a Big Fat Greek Wedding that smashed all audio box office records. The sound that came out was astonishing. The soundstage also moved so far out we had to sublease an apartment next door. The detail that emerged was equally amazing. What was even more extraordinary was that the detail did not overwhelm the music, but rather, made the music incredibly life-like. The music was now in the details, not the other way around. All too sadly often, accurate high-detail systems sound terrible, but this was emphatically not the case here.

The true test of a good system may be to try to use it for background music while doing something else. If you find yourself repeatedly stopping what you are doing and instead sitting down in front of the system to listen, then you know you have a great rig. This is what consistently happened with the TacT/Omega combination. It was the best I-have-to-shut-this-off-or-I-will-never-get-any-work-done audio system I have yet encountered. It also didn't matter what was played through the TacT and the Omegas, from Bach to B.B. King the music that came out simply stopped you in your tracks. For sheer emotion and musicality, the TacT and the Omega's are a marriage made in heaven, despite the Millennium's cold all-digital heart. I also tried the Millennium with a pair of conventional driver speakers, the Impulse Ta'Us horn speakers, and got equally great results.

We could go on about what happened with all the CDs we put to the Millennium test, but by now you have the idea. The TacT Millennium is a seminal event in audio reproduction. Its strengths are so compelling and its revelations so sweeping, it's not an issue of whether other "amplifiers" will one day make music this way. It's just a question of when most all of them do. Whether they will do it as well as the Millennium is another story, however.